Stability of the Rock Mass Reserved in front of Anti-slide Piles

Dapeng Zhu,Lei He,Liangkai Qin 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

To study the stability evaluation method and failure mode of reserved rock masses, the Yueyang landslide project was taken as the research object. First, based on the limit equilibrium method and elastic mechanics, the formulas for calculating the stability of a reserved rock mass were analyzed. Second, the failure modes of the reserved rock mass were tested by the experiment model. The results show that the failure modes of the reserved rock mass can be divided into three modes: upward sliding failure, downward sliding failure and tensile crack failure, which are mainly related to the strength and width of the reserved rock mass. Therefore, it is unreasonable to regard a reserved rock mass as a unified failure form in the design of anti-slide pile reinforcement. In addition, although both moderate-strength and strong-strength reserved rock masses exhibit tensile crack failure, moderate-strength rock masses under triangular loading are prone to tension-sliding failure, while strong-strength rock masses under parabolic loading are prone to tension-overturning failure. Finally, the displacement and stress monitoring results in the experiment are basically consistent with the theoretical analysis, indicating that the theoretical analysis results have high reliability.

Zeolite-catalyzed Isomerization of 1-Hexene to trans-2-Hexene: An ONIOM Study

Li, Yan-Feng,Zhu, Ji-Qin,Liu, Hui,He, Peng,Wang, Peng,Tian, Hui-Ping Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.6

Details of the double-bond isomerization of 1-hexene over H-ZSM-5 were clarified using density functional theory. It is found that the reaction proceeds by a mechanism which involves the Br${\o}$nsted acid part of the zeolite solely. According to this mechanism, 1-hexene is first physically adsorbed on the acidic site, and then, the acidic proton transfers to one carbon atom of the double bond, while the other carbon atom of the double bond bonds with the Br${\o}$nsted host oxygen, yielding a stable alkoxy intermediate. Thereafter, the Br${\o}$nsted host oxygen abstracts a hydrogen atom from the $C_6H_{13}$ fragment and the C-O bond is broken, restoring the acidic site and yielding trans-2-hexene. The calculated activation barrier is 12.65 kcal/mol, which is in good agreement with the experimental value. These results well explain the energetic aspects during the course of double-bond isomerization and extend the understanding of the nature of the zeolite active sites.

Zeolite-catalyzed Isomerization of 1-Hexene to trans-2-Hexene: An ONIOM Study

Yan-Feng Li,Ji-Qin Zhu,Peng He,Peng Wang,Hui-Ping Tian,Hui Liu 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.6

Details of the double-bond isomerization of 1-hexene over H-ZSM-5 were clarified using density functional theory. It is found that the reaction proceeds by a mechanism which involves the Brønsted acid part of the zeolite solely. According to this mechanism, 1-hexene is first physically adsorbed on the acidic site, and then,the acidic proton transfers to one carbon atom of the double bond, while the other carbon atom of the double bond bonds with the Brønsted host oxygen, yielding a stable alkoxy intermediate. Thereafter, the Brønsted host oxygen abstracts a hydrogen atom from the C_6H_13 fragment and the C.O bond is broken, restoring the acidic site and yielding trans-2-hexene. The calculated activation barrier is 12.65 kcal/mol, which is in good agreement with the experimental value. These results well explain the energetic aspects during the course of double-bond isomerization and extend the understanding of the nature of the zeolite active sites.

Identification and quantification of oleanane triterpenoid saponins and potential analgesic and anti-inflammatory activities from the roots and rhizomes of Panax stipuleanatus

Pan-Pan Shu,Lu-Xi Li,Qin-Min He,Jun Pan,Xiao-Lei Li,Min Zhu,Ye Yang,Yuan Qu 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.2

Background: Panax stipuleanatus represents a folk medicine for treatment of inflammation. However, lack of experimental data does not confirm its function. This article aims to investigate the analgesic and anti-inflammatory activities of triterpenoid saponins isolated from P. stipuleanatus. Methods: The chemical characterization of P. stipuleanatus allowed the identification and quantitation of two major compounds. Analgesic effects of triterpenoid saponins were evaluated in two models of thermal- and chemical-stimulated acute pain. Anti-inflammatory effects of triterpenoid saponins were also evaluated using four models of acetic acid-induced vascular permeability, xylene-induced ear edema, carrageenan-induced paw edema, and cotton pellet-induced granuloma in mice. Results: Two triterpenoid saponins of stipuleanosides R₁ (SP-R₁) and R₂ (SP-R₂) were isolated and identified from P. stipuleanatus. The results showed that SP-R₁ and SP-R₂ significantly increased the latency time to thermal pain in the hot plate test and reduced the writhing response in the acetic acid-induced writhing test. SP-R₁ and SP-R₂ caused a significant decrease in vascular permeability, ear edema, paw edema, and granuloma formation in inflammatory models. Further studies showed that the levels of inflammatory mediators, nitric oxide, malondialdehyde, tumor necrosis factor-α, and interleukin 6 in paw tissues were downregulated by SP-R₁ and SP-R₂. In addition, the rational harvest of three- to five-year-old P. stipuleanatus was preferable to obtain a higher level of triterpenoid saponins. SP-R₂ showed the highest content in P. stipuleanatus, which had potential as a chemical marker for quality control of P. stipuleanatus. Conclusion: This study provides important basic information about utilization of P. stipuleanatus resources for production of active triterpenoid saponins.

review on the research of mechanical problems with different moduli in tension and compression

Jun-yi Sun,Hai-qiao Zhu,Shi-hong Qin,Da-lin Yang,Xiao-ting He 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.9

Most materials exhibit different tensile and compressive strains given the same stress applied in tension or compression. These materials are known as bimodular materials. An important model of bimodular materials is the criterion of positive-negative signs of principal stress proposed by Ambartsumyan. This model is mainly applicable to isotropic materials and deals with the principal stress state in a point. However, due to the inherent complexity of the constitutive relation, FEM based on iterative strategy and analytical methods based on a simplified mechanical model are required. In this paper, we review the basic assumptions of this model and its development, several innovative computational methods, and some important engineering applications. We also discuss the sequent key problems in this field.

Diversity of Endophytic Fungi from Different Verticillium-Wilt-Resistant Gossypium hirsutum and Evaluation of Antifungal Activity Against Verticillium dahliae In Vitro

( Zhi Fang Li ),( Ling Fei Wang ),( Zi Li Feng ),( Li Hong Zhao ),( Yong Qiang Shi ),( He Qin Zhu ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.9

Cotton plants were sampled and ranked according to their resistance to Verticillium wilt. In total, 642 endophytic fungi isolates representing 27 genera were recovered from Gossypium hirsutum root, stem, and leaf tissues, but were not uniformly distributed. More endophytic fungi appeared in the leaf (391) compared with the root (140) and stem (111) sections. However, no significant difference in the abundance of isolated endophytes was found among resistant cotton varieties. Alternaria exhibited the highest colonization frequency (7.9%), followed by Acremonium (6.6%) and Penicillium (4.8%). Unlike tolerant varieties, resistant and susceptible ones had similar endophytic fungal population compositions. In three Verticillium-wilt-resistant cotton varieties, fungal endophytes from the genus Alternaria were most frequently isolated, followed by Gibberella and Penicillium. The maximum concentration of dominant endophytic fungi was observed in leaf tissues (0.1797). The evenness of stem tissue endophytic communities (0.702) was comparatively more uniform than the other two tissues. Eighty endophytic fungi selected from 27 genera were evaluated for their inhibition activity against highly virulent Verticillium dahliae isolate Vd080 in vitro. Thirty-nine isolates exhibited fungistasis against the pathogen at varying degrees. Seven species, having high growth inhibition rates (≥75%), exhibited strong antifungal activity against V. dahliae. The antifungal activity of both volatile and nonvolatile metabolites was also investigated. The nonvolatile substances produced by CEF-818 (Penicillium simplicissimum), CEF-325 (Fusarium solani), CEF-714 (Leptosphaeria sp.), and CEF-642 (Talaromyces flavus) completely inhibited V. dahliae growth. These findings deepen our understanding of cotton-endophyte interactions and provide a platform for screening G. hirsutum endophytes with biocontrol potential.